The anus is a canal at the end of the digestive tract through which feces is expelled.
It is about five inches long and is an extension of the rectum. It is only open during the expulsion of feces, because it is usually kept closed by sphincter muscles, which can be relaxed at will.
Did you know ?
The smallest muscle of the skeleton is the stapedius which measures 1/20th of an inch. It is the activator of the stirrup that sends vibrations from the eardrum to the inner ear.
